WO2018025813A1

WO2018025813A1 - Oil concentration measuring device and oil concentration measuring method

Info

Publication number: WO2018025813A1
Application number: PCT/JP2017/027732
Authority: WO
Inventors: 和久小笠原
Original assignee: アクトファイブ株式会社
Priority date: 2016-08-04
Filing date: 2017-07-31
Publication date: 2018-02-08
Also published as: JP7153923B2; CN109564158A; JPWO2018025813A1

Abstract

Provided is an oil concentration measuring device for measuring the concentration of oil in a cleaning liquid, with which it is not necessary to use a costly spectroscopic element or detecting element, for example. An oil concentration measuring device 10 is provided with: a light radiating unit 104 which radiates radiating light having a measuring wavelength, which is one prescribed wavelength between 280 and 300 nm, onto a liquid to be measured (cleaning liquid); a transmitted light detecting unit 105 which measures the intensity of transmitted light resulting from the radiating light that has been transmitted through the liquid to be measured; and an oil concentration determining unit 1061 which calculates a light absorbency, at the measuring wavelength, of the liquid to be measured, on the basis of the intensity of the transmitted light measured by the transmitted light detecting unit 105, and obtains the concentration of oil in the liquid to be measured, on the basis of the value of the light absorbency, and a calibration curve indicating a relationship between the concentration of the oil and the light absorbency at the measuring wavelength. By using one wavelength between 280 and 300 nm at which molecules that do not have multiple carbon element bonds, included in hydrocarbon based cleaning liquids, which are mainstream industrial cleaning liquids, absorb almost no light, and with which it is possible to detect oil with a low concentration of approximately 50 ppm, a costly spectroscopic element or detecting element, for example, becomes unnecessary.

Description

Oil concentration measuring apparatus and oil concentration measuring method

The present invention relates to an apparatus and a method for measuring the concentration of oil in a cleaning liquid. This oil concentration measuring device and oil concentration measuring method is contained in the cleaning liquid used in industrial cleaning machines that remove oils such as cutting oil, press / punching oil, machine oil, grease, and flux adhering to the workpiece. It is suitably used for measuring the concentration of oil.

The cleaning liquid used in industrial cleaning machines is mainly hydrocarbon cleaning liquid. Since the hydrocarbon-based cleaning liquid does not contain an ozone-depleting substance or chlorine, it has a feature that it has little influence on the environment and the human body. In addition, by utilizing the fact that hydrocarbons have a lower boiling point than the above oil component, the hydrocarbon cleaning liquid is a hydrocarbon after storing the used hydrocarbon cleaning liquid in the distillation tank. It is also possible to recycle by heating to a temperature higher than the boiling point of the oil and lower than the boiling point of the oil component. The hydrocarbon-based cleaning liquid further has a feature that clean steam generated during the distillation regeneration treatment can be used for cleaning and drying of the workpiece (hereinafter referred to as “steam cleaning / drying”). In steam cleaning / drying, the work is stored in a steam cleaning / drying cleaning tank, the surface of the work is cleaned with the steam by introducing the steam into the tank, and then the inside of the tank is rapidly depressurized. By rapidly lowering the boiling point of the cleaning agent, the cleaning agent adhering to the work surface is bumped and vaporized, and the work is dried. In an actual industrial cleaning machine, a workpiece is stored in a liquid cleaning tank in which a hydrocarbon-based cleaning liquid is stored and liquid cleaning is performed, and then steam cleaning and drying are performed for finishing.

When the industrial cleaning machine is continuously operated, the oil removed by the distillation gradually accumulates in the distillation tank, and the oil is mixed into the vapor of the hydrocarbon-based cleaning liquid after the distillation regeneration (cleaning liquid after the regeneration). If it does so, the oil component in vapor | steam will adhere to the surface of a workpiece | work at the time of vapor cleaning and drying, and the capability of washing | cleaning will fall. In order to prevent such a decrease in cleaning ability, it is necessary to keep the oil concentration of the cleaning liquid after regeneration below a predetermined concentration. The predetermined concentration differs depending on the component of the oil component, but it is desirable to set it to 50 to 100 ppm or less in order to prevent the cleaning ability from being lowered regardless of the component. Conventionally, the remaining liquid in the distillation tank containing oil is removed when the number of times the workpiece has been cleaned reaches a predetermined number determined by empirical rules, but if the concentration of oil in the cleaning liquid after regeneration is measured, It is expected that the residual liquid can be removed at an appropriate timing.

In order to measure the oil concentration of the cleaning liquid, for example, the method described in Patent Document 1 can be used. In Patent Document 1, the absorbance is measured using ultraviolet light having a predetermined measurement wavelength determined for each component of the oil contained in the cleaning liquid, and a calibration curve of the oil concentration and the absorbance prepared in advance is prepared. Is used to determine the concentration of oil dissolved in the cleaning liquid. The measurement wavelength for each oil component is, for example, 259 nm for commercially available press oil, 234 nm for commercially available cutting oil, and 250 nm for commercially available flux.

JP 09-061349 A

In the oil concentration measuring device and method described in Patent Document 1, since the measurement wavelength differs for each oil component, light having a plurality of wavelengths must be detected corresponding to the measurement wavelengths. For that purpose, for example, a light source that irradiates the sample (hydrocarbon cleaning liquid) with light including a plurality of wavelengths, a spectroscopic element that splits the light that has passed through the sample for each wavelength, and a wavelength of the light that is split by the spectroscopic element A detector that detects each time is used. In such a configuration, it is necessary to use a spectroscopic element that is an expensive optical element, and it is also necessary to use an expensive detector having a plurality of detection elements provided for each wavelength. Moreover, since data is acquired almost simultaneously for each wavelength, an expensive control device for processing and storing a large amount of data in a short time is required.

The problem to be solved by the present invention is to provide an apparatus and a method for measuring the oil concentration in a cleaning liquid that do not require the use of expensive spectroscopic elements, detection elements, and control equipment.

The oil concentration measuring device in the cleaning liquid according to the present invention made to solve the above problems,
a) a light irradiation unit for irradiating the measurement target liquid with irradiation light having a measurement wavelength which is a predetermined wavelength between 280 and 300 nm;
b) a transmitted light detector that measures the intensity of transmitted light through which the irradiation light has transmitted through the measurement target liquid;
c) Based on the intensity of the transmitted light measured by the transmitted light detection unit, the absorbance at the measurement wavelength of the measurement target liquid is calculated, and the relationship between the absorbance value and the concentration of oil and absorbance at the measurement wavelength is calculated. And an oil concentration determination unit that obtains the concentration of the oil in the measurement target liquid based on a calibration curve that is shown.

As described above, many cleaning liquids such as hydrocarbon cleaning liquids, which are currently mainstream as cleaning liquids for industrial cleaning machines, and other glycol ether cleaning liquids, have multiple (double and triple) bonding of carbon atoms. It consists of molecules that do not have Molecules that do not have such multiple bonds of carbon atoms will absorb light at a wavelength of less than 280 nm, while light absorption will hardly occur at wavelengths of 280 nm or longer. On the other hand, most of oils such as cutting oil, press / punching oil, machine oil, grease, and flux that adhere to the workpiece to be cleaned and are mixed into the cleaning liquid by cleaning contain molecules having multiple bonds of carbon atoms. Molecules having such multiple bonds of carbon atoms have a broad range of wavelengths at which the absorbance peaks depending on the type, but the absorbance is 0 within the wavelength range of 280 to 300 nm regardless of the type of oil. It has a constant value. Furthermore, when the wavelength exceeds 300 nm, it becomes difficult to detect an oil component having a low concentration of about 50 ppm.

Therefore, in the present invention, the intensity of transmitted light is measured at a measurement wavelength which is a predetermined one wavelength between 280 and 300 nm, and the absorbance at the measurement wavelength is calculated based on the intensity, whereby the measurement target liquid (cleaning liquid, measurement The concentration of the oil can be determined based on a calibration curve indicating the relationship between the oil content to be measured and the absorbance at the measurement wavelength while suppressing the influence of light absorption by the target cleaning solution.

According to the oil concentration measuring apparatus according to the present invention, since only one predetermined wavelength is used as the measurement wavelength, it is not necessary to use a spectroscopic element or a detection element for each wavelength. In addition, since the amount of data to be processed simultaneously is smaller than in the case of using a plurality of wavelengths, it is not necessary to use an expensive control device. For example, the oil concentration measuring device can be controlled using a control device (programmable logic controller) of an industrial washing machine without providing a dedicated control device for the oil concentration measuring device according to the present invention. For these reasons, the oil concentration measuring device according to the present invention can reduce the cost.

The oil concentration measuring apparatus according to the present invention can be suitably used for measuring oil components having a low concentration of 50 to 2000 ppm. In addition, since it is suitable for the measurement of such low-concentration oil content, the oil-concentration measurement device according to the present invention is used for the above-described steam cleaning / drying that requires the ability to detect a low-concentration oil content of 50 ppm. It can be suitably used for measuring the oil concentration in the post-regeneration cleaning liquid. Note that the target of oil content measurement by the oil concentration measuring device according to the present invention is not limited to the cleaning liquid after regeneration. It can also be used for obtaining (when the time change of the oil concentration becomes equal to or less than a predetermined value is set as the end timing).

The oil concentration measuring device according to the present invention further includes:
A second light irradiation unit that irradiates the measurement target liquid with a second irradiation light having a second measurement wavelength that is a predetermined one wavelength between 320 and 340 nm;
A second transmitted light detector that measures the intensity of the second transmitted light through which the second irradiation light has passed through the measurement target liquid;
Based on the intensity of the second transmitted light measured by the second transmitted light detection unit, the absorbance at the second measurement wavelength of the measurement target liquid is calculated, and the value of the absorbance and the oil content at the second measurement wavelength are calculated. You may provide the 2nd oil concentration determination part which calculates | requires the density | concentration of the oil content in the said measurement object liquid based on the calibration curve which shows the relationship between a density | concentration and an absorbance.

Thus, in addition to the measurement using the irradiation light having the measurement wavelength which is a predetermined one wavelength between 280 and 300 nm, the second having the second measurement wavelength which is a predetermined one wavelength between 320 and 340 nm. By determining the concentration of oil in the measurement target liquid (cleaning liquid, measurement target cleaning liquid) using the irradiation light, it is possible to increase the measurement accuracy of the absorbance of the oil having a relatively long wavelength at which the absorbance is peaked. Also in this case, it is not necessary to use different wavelengths of light for each type of oil, and it is only necessary to use light of two types of wavelengths, the measurement wavelength and the second measurement wavelength. Further, it is not necessary to use a spectroscopic element, and it is not necessary to provide a large number of transmitted light detection elements (transmitted light detection unit and second transmitted light detection unit). Furthermore, if the measurement target liquid is irradiated with the irradiation light and the second irradiation light at different times, the detector for detecting the transmitted light does not need to recognize the wavelength. This detector can be used. A photodiode can be suitably used for such a detector.

The method for measuring the oil concentration in the cleaning liquid according to the present invention is as follows.
Irradiate the measurement target liquid with irradiation light having a predetermined measurement wavelength of 280 to 300 nm,
Measure the intensity of transmitted light through which the irradiation light has passed through the measurement target liquid,
Based on the intensity of the transmitted light, the absorbance at the measurement wavelength of the measurement target liquid is calculated, and based on the absorbance value and a calibration curve indicating the relationship between the oil content and the absorbance at the measurement wavelength, It is characterized by determining the concentration of oil.

According to the present invention, it is not necessary to use expensive spectroscopic elements, detection elements, and control equipment, and an inexpensive oil concentration measuring apparatus and method in a cleaning liquid can be obtained.

The schematic block diagram which shows the industrial washing machine which has one Embodiment of the oil concentration measuring apparatus which concerns on this invention as a component. The figure which shows the measured value of the spectrum of the transmitted light amount in four types of washing | cleaning liquid which consists of a molecule | numerator which does not have the multiple bond of a carbon atom. The functional block diagram which shows the function of the control part in the oil concentration measuring apparatus of this embodiment. The graph which shows the result of having measured the transmitted light amount of the washing | cleaning liquid which contains one each of four different types of oil. The graph which shows the result of having calculated | required the light absorbency from the transmitted light amount shown in FIG. 6 is a graph showing a calibration curve for each oil component created based on the absorbance shown in FIG. 5. The graph which shows the result of having measured the density | concentration of the oil content in a washing | cleaning liquid with the oil content concentration measuring apparatus and method of this embodiment.

Embodiments of an oil concentration measuring apparatus and method according to the present invention will be described with reference to FIGS.

FIG. 1 shows a schematic configuration of an industrial washing machine 1 having an oil concentration measuring device 10 of this embodiment as a component. The industrial cleaning machine 1 is a device for removing oil adhering to a workpiece. In addition to the oil concentration measuring device 10, the first cleaning tank 11, the second cleaning tank 12, the steam cleaning / drying tank 13, and the temporary It has a storage tank 14, a distillation tank 15, a heat exchanger 16, an ejector 17, a post-regeneration cleaning liquid storage tank 18, and a sample cell cleaning liquid tank 19. In FIG. 1, a thick solid line indicates a liquid flow path, a thick broken line indicates a gas flow path, and a thin straight broken line indicates an electric signal path.

(1) Overall Configuration and Operation of Industrial Cleaning Machine 1 Before describing the oil concentration measuring apparatus 10 of the present embodiment, first, the overall configuration of the industrial cleaning machine 1 and the operation of cleaning the workpiece will be described. The first cleaning tank 11 and the second cleaning tank 12 are provided with an ultrasonic vibrator that applies ultrasonic vibration to the cleaning liquid stored in the tank. Moreover, in order to make it easy to produce cavitation by an ultrasonic wave, the inside of the 1st washing tank 11 and the 2nd washing tank 12 is pressure-reduced with a vacuum pump, and deaeration of a washing | cleaning liquid is performed. After storing the cleaning liquid in the first cleaning tank 11 and the second cleaning tank 12, the work is cleaned by immersing the work in the cleaning liquid and applying ultrasonic vibration. Here, for the reason described later, since the oil content of the cleaning liquid in the second cleaning tank 12 is smaller than the cleaning liquid in the first cleaning tank 11, the work is first cleaned in the first cleaning tank 11. Then, by cleaning the workpiece in the second cleaning tank 12, it is possible to minimize the oil in the cleaning liquid from reattaching to the workpiece.

The steam cleaning / drying tank 13 is a tank for performing steam cleaning and drying on the workpiece cleaned in the second cleaning tank 12. The steam used for steam cleaning / drying is supplied from the distillation tank 15 as described later. The cleaning liquid from which the steam in the steam cleaning / drying tank 13 and the material remaining on the surface of the work are removed is returned to the second cleaning tank 12. Further, the gas generated by the decompression of the first cleaning tank 11 and the second cleaning tank 12 and the evaporation of the cleaning liquid is collected in the temporary storage tank 14.

The distillation tank 15 is provided with a float valve 151, and when the liquid in the distillation tank 15 becomes a predetermined amount or less by distillation, the cleaning liquid is introduced from the temporary storage tank 14 into the distillation tank 15. The distillation tank 15 is heated by a heater (not shown) and depressurized by an ejector 17. As a result, the cleaning liquid evaporates leaving the oil as a liquid. A part of the generated steam is supplied to the steam cleaning / drying tank 13 as described above, and the rest is condensed in the heat exchanger 16 and then stored in the cleaning liquid storage tank 18 after regeneration.

The post-regeneration cleaning liquid from which oil has been removed by the distillation tank 15 flows from the post-regeneration cleaning liquid storage tank 18 into the second cleaning tank 12. The first cleaning tank 11 and the second cleaning tank 12 are connected by a second overflow pipe 122. The second overflow pipe 122 has a higher connection position with the second cleaning tank 12 than a connection position with the first cleaning tank 11, and the cleaning liquid in the second cleaning tank 12 flows due to the inflow of the cleaning liquid after regeneration. When the liquid level becomes higher than the latter connection position, a part of the cleaning liquid in the second cleaning tank 12 naturally moves to the first cleaning tank 11. Accordingly, the cleaning liquid in the second cleaning tank 12 has a smaller oil content than the cleaning liquid in the first cleaning tank 11. Further, the first cleaning tank 11 and the temporary storage tank 14 are connected by a first overflow pipe 112, and the liquid level of the cleaning liquid in the first cleaning tank 11 is caused by the inflow of the cleaning liquid from the second cleaning tank 12. If it becomes higher than the connection position of the pipe | tube 112, a part of washing | cleaning liquid in the 1st washing tank 11 will move to the temporary storage tank 14 through the 1st overflow pipe 112 naturally.

The 1st washing tank 11 has the 1st circulation filtration system 111 which takes out cleaning fluid from a tank, and returns it in a tank through a filter. A similar second circulation filtration system 121 is also provided in the second cleaning tank 12. These circulating filtration systems remove particles having a particle size of about 10 μm or more, and cannot remove oil.

(2) Configuration of Oil Concentration Measuring Device 10 of this Embodiment Next, the configuration of the oil concentration measuring device 10 in the industrial cleaning machine 1 will be described in detail. The oil concentration measuring apparatus 10 includes a flow path 101 connected to the first cleaning tank 11, the second cleaning tank 12, and the post-regeneration cleaning liquid storage tank 18, and a liquid feed pump 102 provided in the flow path 101, as will be described later. And a sample cell 103 provided downstream of the liquid feed pump 102 in the flow channel 101, a reference cell 1031 for reference measurement, a light irradiation unit 104, a transmitted light detection unit 105, and control of the entire apparatus. And a control unit 106 that performs data processing to be described later.

The inflow portion 1011 of the flow path 101 is supplied to the first cleaning tank 11 via the first relay pipe 113, to the second cleaning tank 12 via the second relay pipe 123, and after-regeneration cleaning liquid via the third relay pipe 183. Each is connected to the storage tank 18. The first relay pipe 113 is provided with a first relay on-off valve 11V, the second relay pipe 123 is provided with a second relay on-off valve 12V, and the third relay pipe 183 is provided with a third relay on-off valve 18V. ing.

The outflow part of the channel 101 is connected to the temporary storage tank 14. Therefore, the cleaning liquid used for the measurement in the oil concentration measuring device 10 is distilled by the distillation tank 15 through the temporary storage tank 14, and finally returned to the second cleaning tank 12 in a state where the oil is removed. In addition, you may make it return the washing | cleaning liquid used for the measurement directly from the outflow part to the tank in which the washing | cleaning liquid was accommodated.

Both the sample cell 103 and the reference cell 1031 are quartz cells that absorb less ultraviolet light. The sample cell 103 is connected to the channel 101 during normal measurement, and the reference cell 1031 is connected when measuring reference data. The reference cell 1031 is filled with a cleaning liquid that does not contain oil, and the reference data is measured after interrupting the measurement of the oil concentration at predetermined time intervals under the control of the control unit 106.

In the present embodiment, the light irradiation unit 104 irradiates the cleaning liquid (measurement target liquid) in the sample cell 103 with a predetermined measurement wavelength between 280 and 300 nm, and emits the measurement wavelength. Consists of. In this embodiment, the measurement wavelength is 290 nm.

Here, the reason why the measurement wavelength is set to one wavelength between 280 and 300 nm will be described with reference to FIG. FIG. 2 shows measured values of the spectrum of transmitted light in the four types of cleaning liquids 1 to 4 composed of molecules having no multiple bonds of carbon atoms. Of the four types, cleaning solutions 1 to 3 are all saturated aliphatic hydrocarbon cleaning solutions, and cleaning solution 4 is a glycol ether cleaning solution. FIG. 2 also shows the spectrum of incident light. All of the four types of cleaning liquids have a transmitted light amount that is significantly smaller than the amount of incident light at a wavelength of less than 280 nm, and ultraviolet light is absorbed by the cleaning liquid. On the other hand, when the wavelength is 280 nm or more, the difference between the transmitted light amount and the incident light is small, and the ultraviolet rays are hardly absorbed by the cleaning liquid. Therefore, if the measurement is performed at a measurement wavelength of 280 nm, the concentration of the oil can be measured while suppressing the influence of light absorption by the cleaning liquid. On the other hand, when the measurement wavelength exceeds 300 nm, as shown in FIG. 5 to be described later, the absorbance value due to the oil component at a low concentration (100 ppm in the example shown in FIG. 5 and further 50 ppm) becomes too small. I can't. Therefore, by setting one wavelength between 280 and 300 nm as the measurement wavelength, it is possible to measure the oil concentration even at a low concentration of about 50 ppm while suppressing the influence of light absorption by the cleaning liquid.

The transmitted light detection unit 105 detects the intensity of transmitted light having the measurement wavelength that has passed through the cleaning liquid in the sample cell 103, and includes a photodiode and a signal conversion unit. The photodiode detects the light of the measurement wavelength and outputs the intensity as an analog signal. The signal converter converts the analog signal output from the photodiode into a digital signal.

The control unit 106 has the functions shown in the functional block diagram of FIG. As the control unit 106, a programmable logic controller or a personal computer can be used, and a control device of an industrial cleaning machine may be applied as it is, or a control device of the oil concentration measuring device 10 may be provided. . The control unit 106 includes an oil concentration determination unit 1061, a reference data recording unit 1062, a calibration curve recording unit 1063, a condition input unit 1064, and a measurement control unit 1065. The oil concentration determination unit 1061 includes an absorbance calculation unit 1061A, a calibration curve selection unit 1061B, and a calibration curve application unit 1061C. Details of the oil concentration determination unit 1061 will be described later together with the operation of the oil concentration measuring apparatus 10 of the present embodiment. The reference data recording unit 1062 records transmitted light amount data (reference data) at the measurement wavelength, which is measured in advance for a cleaning agent that does not contain oil. The calibration curve recording unit 1063 includes, for each oil component that can be used for processing the workpiece, the concentration and absorbance of the oil component at the measurement wavelength created based on data measured in advance using a sample having a known oil component concentration. A calibration curve showing the relationship is recorded. In addition, when components are close to each other between a plurality of processing oils having different manufacturers and model numbers, a common calibration curve may be used for the plurality of processing oils. The condition input unit 1064 is used by the measurer to input measurement conditions described later using an input device such as a touch panel. The measurement control unit 1065 controls the start and end of light irradiation from the light source in the light irradiation unit 104 and the start and end of the processing of each unit.

The sample cell cleaning liquid tank 19 is a tank in which a cleaning liquid for cleaning the sample cell 103 (the same as the cleaning liquid that is the target of oil concentration measurement) is stored.

(3) Operation of Oil Concentration Measuring Device 10 of the Present Embodiment The operation of the oil concentration measuring device 10 of the present embodiment will be described. Here, a case will be mainly described in which the post-regeneration cleaning liquid stored in the post-regeneration cleaning liquid storage tank 18 that is close to the oil concentration in the steam used in the steam cleaning / drying tank 13 is an oil concentration measurement target.

First, measurement is started when the measurer inputs a predetermined measurement condition in the condition input unit 1064 and then inputs a measurement start instruction. The measurement condition input here is information (for example, manufacturer and model number of the processing oil) for specifying the processing oil attached to the workpiece to be cleaned using the cleaning liquid to be measured.

When measurement is started, first, the cleaning tank storing the cleaning liquid to be measured or the relay valve corresponding to the storage tank is opened. Here, the third relay open / close valve 18V provided in the third relay pipe 183 connected to the post-regeneration cleaning liquid storage tank 18 is opened. As a result, the post-regeneration cleaning liquid to be measured is introduced into the sample cell 103 through the channel 101. If the cleaning liquid to be measured is the cleaning liquid in the first cleaning tank 11, the first relay on / off valve 11V is opened, and if the cleaning liquid in the second cleaning tank 12 is to be opened, the second relay on / off valve 12V is opened.

The light irradiation unit 104 irradiates the cleaning liquid in the sample cell 103 with light having the measurement wavelength (290 nm). The transmitted light detection unit 105 measures the intensity I of the transmitted light amount that has passed through the cleaning liquid, converts it into a digital signal, and outputs it.

Next, the control unit 106 inputs a digital signal indicating the intensity I of the transmitted light amount output from the transmitted light detection unit 105 and transmits the transmitted light amount at the measurement wavelength of the cleaning liquid not containing oil from the reference data recording unit 1062. Reference data I ₀ is acquired. The absorbance calculation unit 1061A of the control unit 106 obtains the absorbance A = log ₁₀ (I ₀ / I) of the cleaning liquid to be measured based on the transmitted light intensity I in the cleaning liquid to be measured and the reference data I ₀ .

Subsequently, the calibration curve selection unit 1061B of the control unit 106 generates a calibration curve corresponding to the specified processing oil based on the information for specifying the processing oil input by the condition input unit 1064. Get from. Then, the calibration curve application unit 1061C applies the absorbance A of the cleaning liquid to be measured obtained by the absorbance calculation unit 1061A to the calibration curve selected by the calibration curve selection unit 1061B, and obtains the concentration of the processing oil.

Thereafter, the concentration of the processing oil is repeatedly obtained by repeatedly introducing the cleaning liquid after regeneration to the sample cell 103 into the sample cell 103 and repeatedly performing the light irradiation by the light irradiation unit 104 and the measurement of the intensity I of the transmitted light amount. When the concentration of the processing oil exceeds a predetermined value, the residual liquid remaining in the distillation tank 15 is processed. The treatment of the residual liquid is performed by separating the cleaning liquid and the processing oil in the residual liquid by boiling the residual liquid, thereby discarding the processing oil remaining in the distillation tank 15.

When the cleaning liquid to be measured is the cleaning liquid in the first cleaning tank 11 or the second cleaning tank 12, the concentration of the processing oil in the cleaning liquid is repeatedly obtained by the same method as described above during the cleaning of the workpiece. The measurement result can be used to determine the timing of completion of cleaning, that is, the cleaning of the workpiece is terminated when the change with time of the concentration becomes a predetermined value or less.

(4) Absorbance and calibration curve examples Prepare multiple samples of four types of oil (Table 1) selected as typical processing oils in the same cleaning solution at different concentrations, and transmit light quantity for each oil and concentration. Was measured to determine the absorbance. Here, in order to verify the validity of setting the measurement wavelength to 290 nm, the amount of transmitted light was measured within the range of 260 to 400 nm without limiting the wavelength to 290 nm. Here, “NS100” (manufactured by JX Energy Co., Ltd., cleaning liquid 1 in FIG. 2), which is a saturated aliphatic hydrocarbon-based cleaning liquid having no multiple bonds of carbon atoms, was used as the cleaning liquid. In addition, the concentration of each oil was 100 ppm, 500 ppm, 2000 ppm, and 10000 ppm.

The amount of transmitted light obtained by the measurement is shown in FIG. 4 for each oil contained in the cleaning liquid. Moreover, the result of having calculated | required the light absorbency based on the transmitted light amount shown in FIG. 4 is shown in FIG. In any case, within the wavelength range of 280 to 300 nm, the absorbance has a different value depending on the oil concentration.

Based on the oil content at a wavelength of 290 nm and the absorbance at each concentration thus obtained, a calibration curve showing the relationship between the absorbance and the concentration was prepared for each oil content. The prepared calibration curve is shown in FIG. For each oil, data with a concentration of 10,000 ppm is not used because it deviates from the straight line in the calibration curve. As shown in FIG. 6, when the concentration is 2000 ppm or less, the calibration curve can be shown as a straight line. Therefore, at a concentration of at least 2000 ppm, the oil concentration can be measured by the oil concentration measuring apparatus and method of this embodiment.

In the industrial washer shown in FIG. 1, it is important to measure and manage the oil concentration of the regenerated cleaning liquid that is distilled and regenerated in the distillation tank 15 in order to maintain the quality of workpiece cleaning. In particular, since the steam generated in the distillation tank 15 is used as it is in the steam cleaning / drying tank 13 for steam cleaning, which is the finishing cleaning of the workpiece, the oil concentration is measured and managed continuously by an industrial cleaning machine. Most important to do while driving. According to the present invention, it is possible to measure and manage the oil concentration during continuous operation of such an industrial washer.

Using the obtained calibration curve, an experiment was conducted to measure the concentration of oil in the cleaning liquid after regeneration. Also in this experiment, the above-mentioned NS100 or NS200 (manufactured by JX Energy Co., Ltd., cleaning liquid 2 in FIG. 2) was used as the cleaning liquid, and the oils to be added included five types of cutting including those shown in Table 1 above. Oil and 5 kinds of press and punching oil were used. In this experiment, a sample with a known concentration (this concentration is referred to as the “original concentration”) is prepared by weighing the cleaning solution and the oil and mixing them, and then comparing the original concentration with the measured value. went.

The experimental results are shown in the graph of FIG. In this graph, the original concentration is plotted on the horizontal axis and the measured value is plotted on the vertical axis. The data point falls between the two dashed lines in the graph if the measured value is within ± 10% of the original concentration. In FIG. 7, data for all samples are shown in one graph. As shown in this graph, all the measured values obtained this time are generally within ± 10% of the original concentration. An accuracy of about ± 10% is sufficient for use in industrial washing machines.

(5) Modification In the oil concentration measuring apparatus 10 of the present embodiment, the light irradiation unit 104 irradiates the cleaning liquid with light having a measurement wavelength between 280 and 300 nm (290 nm in the above example). The cleaning liquid may be irradiated with a second measurement wavelength that is a predetermined wavelength of 340 nm. Such two different wavelengths of light are preferably generated using two light sources that emit monochromatic light and have different wavelengths of monochromatic light. In this case, as long as the transmitted light detection unit 105 can measure the intensities of both the light having the measurement wavelength and the light having the second measurement wavelength, only one light can be detected in common. I just need it. Or you may use the transmitted light detection part which changes for every wavelength. Similarly to the case of the measurement wavelength (290 nm), a calibration curve showing the relationship between absorbance and concentration can be created for each oil component based on the absorbance data in FIG.

For example, the calibration curve shown in Fig. 6 (d) has a slightly larger difference between the point where the absorbance was obtained and the calibration curve than the calibration curves (a) to (c). Thus, the accuracy can be increased by obtaining the oil concentration.

DESCRIPTION OF SYMBOLS 1 ... Industrial washing machine 10 ... Oil concentration measuring device 101 ... Flow path 1011 ... Inflow part 102 ... Liquid feeding pump 103 ... Sample cell 1031 ... Reference cell 104 ... Light irradiation part 105 ... Transmitted light detection part 106 ... Control part 1061 ... Oil concentration determination unit 1061A ... absorbance calculation unit 1061B ... calibration curve selection unit 1061C ... calibration curve application unit 1062 ... reference data recording unit 1063 ... calibration curve recording unit 1064 ... condition input unit 1065 ... measurement control unit 11 ... first cleaning tank 111 ... 1st circulation filtration system 112 ... 1st overflow pipe 113 ... 1st relay pipe 11V ... 1st relay on-off valve 12 ... 2nd washing tank 121 ... 2nd circulation filtration system 122 ... 2nd overflow pipe 123 ... 2nd relay pipe 12V ... second relay opening / closing valve 13 ... steam cleaning / drying tank 14 ... temporary storage tank 15 ... distillation tank 151 ... float valve 16 ... heat exchanger 17 Ejector 18 ... playback after the cleaning liquid storage tank 183 ... third relay pipe 18V ... third relay off valve 19 ... sample cell washing solution tank

Claims

a) a light irradiation unit for irradiating the measurement target liquid with irradiation light having a measurement wavelength which is a predetermined wavelength between 280 and 300 nm;
b) a transmitted light detector that measures the intensity of transmitted light through which the irradiation light has transmitted through the measurement target liquid;
c) Based on the intensity of the transmitted light measured by the transmitted light detection unit, the absorbance at the measurement wavelength of the measurement target liquid is calculated, and the relationship between the absorbance value and the concentration of oil and absorbance at the measurement wavelength is calculated. An oil concentration measuring device in cleaning liquid, comprising: an oil concentration determining unit that obtains the concentration of oil in the measurement target liquid based on a calibration curve that is shown.
further,
A second light irradiation unit that irradiates the measurement target liquid with a second irradiation light having a second measurement wavelength that is a predetermined one wavelength between 320 and 340 nm;
A second transmitted light detector that measures the intensity of the second transmitted light through which the second irradiation light has passed through the measurement target liquid;
Based on the intensity of the second transmitted light measured by the second transmitted light detection unit, the absorbance at the second measurement wavelength of the measurement target liquid is calculated, and the value of the absorbance and the oil content at the second measurement wavelength are calculated. The apparatus for measuring an oil concentration in a cleaning liquid according to claim 1, further comprising a second oil concentration determining unit that obtains the concentration of the oil in the measurement target liquid based on a calibration curve indicating a relationship between the concentration and the absorbance. .
Irradiate the measurement target liquid with irradiation light having a predetermined measurement wavelength of 280 to 300 nm,
Measure the intensity of transmitted light through which the irradiation light has passed through the measurement target liquid,
Based on the intensity of the transmitted light, the absorbance at the measurement wavelength of the measurement target liquid is calculated, and based on the absorbance value and a calibration curve indicating the relationship between the oil content and the absorbance at the measurement wavelength, A method for measuring the concentration of oil in a cleaning liquid, characterized in that the concentration of oil is determined.
4. The method for measuring an oil concentration in a cleaning liquid according to claim 3, wherein the liquid to be measured is composed of molecules having no multiple bonds of carbon atoms.
further,
Irradiating the measurement target liquid with second irradiation light having a second measurement wavelength which is a predetermined one wavelength between 320 and 340 nm;
Measuring the intensity of the second transmitted light through which the second irradiation light has passed through the measurement target liquid;
Based on the intensity of the second transmitted light, the absorbance at the second measurement wavelength of the measurement target liquid is calculated, and based on the absorbance value and a calibration curve indicating the relationship between the oil content and the absorbance at the second measurement wavelength. The oil concentration measurement method in the cleaning liquid according to claim 3 or 4, wherein the oil concentration in the measurement target liquid is obtained.